1. Field of the Invention
Aspects of the present invention relate to an apparatus for acquiring a global positioning system (GPS) signal, and more particularly, to a GPS receiver which speedily acquires a GPS signal, and a method and apparatus for controlling power supply to the GPS receiver.
2. Description of the Related Art
A conventional global positioning system (GPS) receiver calculates its own location by receiving location signals of at least 4 GPS satellites. When power is supplied to the GPS receiver, the GPS receiver searches for the satellite location signals through a GPS antenna and calculates its own location using location information received through the GPS antenna.
FIG. 1A is a block diagram illustrating a conventional GPS receiver. An external power jack is inputted to a power jack input unit 110. A main power supply unit 120 converts power received from the external power jack through the power jack input unit 110 to a rated voltage of the GPS receiver. At this time, when a power switch SW1 is turned on, the rated voltage is supplied to a control unit 140 and a GPS power supply unit 130 from the main power supply unit 120.
Upon receiving the rated voltage from the main power supply unit 120, the control unit 140 performs a booting operation in order to execute a navigation program. Here, when the navigation program is executed, the control unit 140 generates a GPS power enable signal which drives the GPS power supply unit 130.
Upon receiving the GPS power enable signal from the control unit 140, the GPS power supply unit 130 converts the rated voltage supplied from the main power supply unit 120 to a driving voltage of a GPS module unit 150. Accordingly, the GPS module unit 150 performs an initial operation for searching for a satellite signal through a GPS antenna (not shown) according to the driving voltage supplied from the GPS power supply unit 130. The GPS module unit 150 transmits the location information received through the GPS antenna to the control unit 140 when the initial operation during a predetermined time is completed, and receives a control command from the control unit 140.
FIG. 1B is a timing diagram for describing an acquisition of a GPS signal in a GPS receiver. First, when an external power is inputted through the power jack 110 in (a), a power switch SW1 is turned on after a user time in (b). Then, when the power switch SW1 is turned on, an operating system (OS) loading is performed by the control unit 140 in (c). After performing the OS loading, a navigation program is loaded by the control unit 140 in (d).
Next, after loading the navigation program for a predetermined time, a GPS signal is acquired by GPS module unit 150 in (e). Here, a GPS on and signal acquisition time is a difference between the GPS signal acquisition starting time in (e) and the navigation program loading starting time in (d). Also, a user slowdown speed time is a difference between the GPS signal acquisition starting time in (e) and the power switch on time in (b).
As illustrated in FIG. 1B, according to a conventional method of acquiring a GPS signal, when an external power is supplied, a GPS signal is acquired after the OS loading time in (c) and the navigation program executing time in (d) are all completed. Accordingly, there is a long waiting time for the GPS signal since the OS loading time in (c) and the navigation program executing time in (d) can only be started and completed after the power switch SW1 is turned on in (b).